Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

321
FXUS63 KLOT 271159
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
559 AM CST Tue Jan 27 2026

.KEY MESSAGES...

- Southwest winds turning northwest this morning with gusts
  around 30 to 35 mph. Some blowing and drifting snow possible.

- Isolated to scattered gusty snow showers this morning, mainly
  north and east of a Rochelle to Rensselaer line. Flurries
  then possible through the afternoon area-wide.

- Cold conditions will continue into the weekend with mainly
  subzero wind chills through Saturday morning.

- Threat for impactful lake effect snow for northeast IL and
  northwest IN Thursday night through Saturday night.

&&

.DISCUSSION...
Issued at 241 AM CST Tue Jan 27 2026

Early-morning objective analysis places a roughly 1004 mb
surface low just northeast of Lake Superior with an attendant
cold front slicing across Wisconsin and just about to cross into
northwest Illinois. A concentrated area of gusty snow showers
continues to track steadily south and east out of southwest
Wisconsin immediately along and just behind the aforementioned
frontal boundary. Latest guidance is generally doing a poor job
handling the degree of boundary layer moistening which is
obviously receiving a boost from the notable large scale
dynamics associated with the parent upper-level wave. Have
introduced chances for snow showers mainly north and east of a
Rochelle to Rensselaer line through about mid morning.

Timing out the salient upstream features brings initial snow
showers south of the WI state line in the 4-6 AM window, and
then south and eastward across the region through mid morning.
These initial snow showers, which are aligned within NW-SE
horizontal convective rolls do not look particularly robust and
organized at this time. This matches the environmental parameter
space, with generally limited low-level instability and
relatively thin and scattered-looking cloud cover. A somewhat
more organized cluster of snow showers with reflectivities
nearing 25-30 dBZ at times from the La Crosse, WI radar along
the main frontal boundary may persist into the region this
morning. Latest timing brings this to the state line just after
6 AM, into the Chicago area through 7 to 8 AM, and then across
parts of NW Indiana through 8 to 10 AM. With the snow squall
parameter space not particularly robust, fast forward motions
limiting residence and accumulation time, and visibilities
generally remaining above one mile upstream, not terribly
concerned with a true snow squall issue this morning as this
activity tracks overhead, but will message the potential for
gustier snow showers which could lay down a quick dusting/light
coating in spots through the morning rush hour.

As the main front sweeps through, northwesterly winds will
increase with gusts briefly around 35 mph before easing into the
25-30 mph range this afternoon. Intermittent flurries will be
possible within any lingering scattered to broken stratus layer,
but guidance indicates we should steadily lose the bulk of the
BL moisture through late afternoon and evening, which should
bring any lingering flurry/snow shower potential to an end. The
one exception will be near the lake as colder air spills into
the region this afternoon. As this occurs, the main lake effect
snow shield will build westward a bit. While the vast majority
of LES will remain east of our region given the largely WNW/NW
boundary layer flow, it`s possible that some flurries or light
snow develops as far west as parts of northeast Porter County
this afternoon and evening.

Conditions look quiet tonight. Depending on temperature trends,
it`s possible some spots could flirt with the 20 below advisory
criteria, but this currently does not appear long-lived and
widespread enough to warrant the issuance of another Cold
Weather Advisory into Wednesday morning at this time.

On Wednesday, the next shortwave trough will sweep across the
Great Lakes. The trend towards a generally drier outcome
persists tonight, with no indications of an accumulating snow
threat in our area into Wednesday night, with the main axis of
deeper saturation pushed well to our south.

The main focus during the end of the week and into the upcoming
weekend remains on the potential for another round of
accumulating lake effect snow (potentially a long-duration
event) as another sprawling ~1050 mb arctic high descends out of
Saskatchewan and Manitoba late Thursday night into Friday. As
this occurs, 850 mb temperatures are forecast to drop to around
minus 20 C, which in turn will result in building inversion
heights over the lake. LES parameters certainly look sufficient
to support periods of more intense lake effect snow, with lake-
induced ELs nearing 9-10 kft at times, especially through Friday
with 850 mb temps forecast to warm through Saturday.

Initial LES looks to develop late Thursday night into early
Friday morning. It`s possible that this initial activity has a
somewhat difficult time organizing given some degree of wind
shear in the boundary layer as a synoptic scale trough pivots
southwest out of the Upper Great Lakes. By later Friday night
and Saturday, however, guidance depicts generally lessening
shear as the bulk of the atmospheric flow shifts northeasterly.
Guidance then depicts LES organizing into a single dominant band
during this time as low-level convergence maximizes down the
long axis of the lake. During this time, ELs are forecast to
fall a bit as 850 mb temps warm, which may have a bit of a
modulating effect on LES intensity. That said, given the progged
increasing convergence, even 6-7 kft ELs will be more than
sufficient to support periods of heavier snowfall.

At this point, it remains too early to hone in on specifics, but
guidance trends continue towards an impactful period of lake
effect snow in our area, including Chicago, parts of NE and
east-central Illinois, and NW Indiana from late Thursday night
through Saturday night, and possibly even through Sunday.
Guidance at this time does indicate the potential for quite a
bit of band wobbling, which in turn could limit residence times
and overall totals, but a more quasistationary north-south
oriented band is also advertised (CMC, UKMET for example).
Temperatures in the teens and single digits will have the
potential to exacerbate impacts due to a very light/fluffy snow
and lessened effectiveness of road treatments.

Beyond this weekend, there`s another signal for another period
of light accumulating snowfall early next week.

Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 559 AM CST Tue Jan 27 2026

Key Messages:

- Blustery west-northwesterly winds will occur today.

- A few light snow showers may be observed at ORD, MDW, and GYY
  this morning. Flurries also couldn`t be ruled out later this
  afternoon.

- Periods of MVFR ceilings remain possible this morning and
  afternoon.


A cold front is dropping through the area this morning, with
winds turning west-northwesterly behind it. Regular gusts in the
20-30 kt range can be expected through this afternoon behind the
front, while sustained winds generally remain between 15 and 20
kts.

Widely scattered snow showers are evident on area radars near
the front early this morning. The more robust snow showers
should remain north/northeast of the terminals, but ORD, MDW,
and GYY may still get grazed by some of this activity, perhaps
resulting in a brief period of MVFR visibilities.

MVFR ceilings may also briefly be observed with the morning
snow showers. Some model guidance is also suggesting that MVFR
ceilings may then be observed later this afternoon, though a
relative lack of upstream MVFR ceilings at press time makes
this an item of lower confidence at this time, so have VFR
conditions prevailing in the TAFs for now. Wherever any
MVFR/low-end VFR ceilings materialize later today, non-
accumulating flurries may be observed at times.

Ogorek

&&

.HYDROLOGY...
Issued at 230 PM CST Fri Jan 23 2026

River gauges, reports from local officials, and reports from
trained ice spotters continue to indicate a few ice jams across
the area due to the significant increase in river ice over
recent days. With continued cold weather into next week,
conditions will remain favorable for river ice formation. While
no widespread flooding is expected, localized ice jams may
occur.

- NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 6 PM CST this evening for the IL
     and IN nearshore waters.

&&

$$

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